Bug 1275 - No preview in Spectral edit effects

Introduces a new type 'spectral' t Nyquist plug-ins

plug-ins/SpectralEditParametricEQ.ny

@@ -1,41 +1,28 @@
 ;nyquist plug-in
 ;version 4
-;type process
+;type process spectral
 ;preview linear
 ;name "Spectral edit parametric EQ..."
 ;action "Filtering..."
 ;author "Paul Licameli"
 ;copyright "Released under terms of the GNU General Public License version 2"
 
-
 ;; SpectralEditParametricEQ.ny by Paul Licameli, November 2014.
-;; Updated to version 4 by Steve Daulton November 2014.
+;; Updated by Steve Daulton 2014 / 2015.
 ;; Released under terms of the GNU General Public License version 2:
 ;; http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 
 ;control control-gain "Gain (dB)" real "" 0 -24 24
 
-(setf control-gain (min 24 (max -24 control-gain))) ; excessive settings may crash
-
-(defmacro validate (hz)
-"Ensure frequency is below Nyquist"
-  `(setf ,hz (max 0 (min (/ *sound-srate* 2.0) ,hz))))
-
-(defun wet (sig gain f0 f1)
-  ;; (re)calculate bw and fc to ensure we do not exceed Nyquist frequency
-  (validate f0)
-  (validate f1)
-  (let ((fc (sqrt (* f0 f1)))
-	(bw (/ (log (/ f1 f0))
-	       (log 2.0))))
-    (when (= bw 0)
-      (throw 'error-message (format nil "~aBandwidth is zero.~%Select a frequency range." p-err)))
-    (eq-band sig fc gain (/ bw 2))))
+(defun wet (sig gain fc bw)
+  (eq-band sig fc gain (/ bw 2)))
 
 (defun result (sig)
   (let*
       ((f0 (get '*selection* 'low-hz))
        (f1 (get '*selection* 'high-hz))
+       (fc (get '*selection* 'center-hz))
+       (bw (get '*selection* 'bandwidth))
        (tn (truncate len))
        (rate (snd-srate sig))
        (transition (truncate (* 0.01 rate)))  ; 10 ms
@@ -44,18 +31,34 @@
        (breakpoints (list t1 1.0 t2 1.0 tn))
        (env (snd-pwl 0.0 rate breakpoints)))
     (cond
-      ((not (or f0 f1))
-        (throw 'error-message (format nil "~aPlease select frequencies." p-err)))
-      ((or (not f0) (= f0 0))
-         (throw 'error-message (format nil "~aLow frequency is undefined." p-err)))
+      ((not (or f0 f1)) ; This should never happen for a 'spectral' effect.
+          (throw 'error-message (format nil "~aPlease select frequencies." p-err)))
+      ((not f0)
+          (throw 'error-message (format nil "~aLow frequency is undefined." p-err)))
       ((not f1)
-         (throw 'error-message (format nil "~aHigh frequency is undefined." p-err)))
-      ;; If seleted frequency band is above Nyquist, do nothing.
-      ((< f0 (/ *sound-srate* 2.0))
-          (sum (prod env (wet sig control-gain f0 f1)) (prod (diff 1.0 env) sig))))))
+          (throw 'error-message (format nil "~aHigh frequency is undefined." p-err)))
+      ((and fc (= fc 0))
+          (throw 'error-message (format nil "~aCenter frequency must be above 0 Hz." p-err)))
+      ((and f1 (> f1 (/ *sound-srate* 2)))
+          (throw 'error-message
+            (format nil "~aFrequency selection is too high for track sample rate.
+                        For the current track, the high frequency setting cannot~%~
+                        be greater than ~a Hz"
+                    p-err (/ *sound-srate* 2))))
+      ((and bw (= bw 0))
+          (throw 'error-message
+            (format nil "~aBandwidth is zero (the upper and lower~%~
+                         frequencies are both ~a Hz).~%~
+                         Please select a frequency range."
+                    p-err f0)))
+      ;; If centre frequency band is above Nyquist, do nothing.
+      ((and fc (>= fc (/ *sound-srate* 2.0)))
+          nil)
+      (t  (sum (prod env (wet sig control-gain fc bw))
+               (prod (diff 1.0 env) sig))))))
 
 (catch 'error-message
-  (setf p-err "")
-  (if (= control-gain 0)		; Allow dry preview
-      "Gain is zero. Nothing to do."
-    (multichan-expand #'result *track*)))
+  (setf p-err "Error.\n")
+  (if (= control-gain 0)
+      nil ; Do nothing
+      (multichan-expand #'result *track*)))